The figure shows a container made up of 3 sections. Cuboid T with a square base of side 4 cm and height 26 cm. Cube U with a side of 10 cm. Cuboid V that is 60 cm by 20 cm by 49 cm. Water from a tap above flows down at a rate of 3.2 litres per minute while water is drained out from the bottom at a rate of 2 litre per minute. How long did it take to fill up the container to a height of 69 cm from the base? Give the answer in minutes correct to nearest whole number.
Volume of U
= 10 x 10 x 10
= 1000 cm³ 

Volume of V
= 60 x 20 x 49
= 58800 cm³ 

2 ℓ = 2000 cm³ 
3.2 ℓ = 3200 cm³ 

Net increase in volume per minute
= 3200 - 2000
= 1200 cm³/min

Height of T to be filled with water
= 69 - (49 + 10)
= 10 cm

Volume of water in T
= 4 x 4 x 10
= 160 cm³ 

Volume of water in V, U and part of T
= 58800 + 1000 + 160
= 59960 cm³ 

Time taken to reach height
= 59960 ÷ 1200
≈ 50 min (Correct to nearest whole number)

Answer(s): 50 min